JPS5928626B2 - Mitsushi Metal for Hydrogen Storage - Manufacturing method of nickel-based quaternary alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in the production method of Mitsushimetal-nickel based quaternary alloys for hydrogen storage, and in particular to improvements in the hydride composition in the flat region of hydrogen storage and dissociation pressure characteristics at a constant temperature, the so-called plateau region. The present invention relates to a method for producing an alloy having the property of requiring low hydrogenation pressure.

It has been well known that certain metals or alloys react with hydrogen under appropriate pressure and temperature to produce metal hydrides.

Compared to other solid-gas reactions, this reaction has good reversibility, a high reaction rate, and a large amount of heat storage per unit weight or unit volume, so metal hydrides are used in various energy conversion materials. It is being considered for use in systems such as

By the way, in the case of such uses, one of the extremely important properties in practice is the hydrogen absorption and dissociation properties at a constant temperature.
In particular, it is required that the plateau region be flat and that the pressure change with respect to the hydride composition be small.

However, multi-component alloys for hydrogen storage are generally produced by directly melting the component metals in an argon arc furnace, high frequency furnace, etc.
Because it is manufactured by mixing, a rapid change from liquid to solid occurs during the cooling process, and it solidifies with unstable lattice gaps, resulting in a single-phase alloy. The disadvantage was that it became larger.

Therefore, the present invention aims to eliminate such conventional drawbacks, and the obtained alloy is single-phase, and the interstitial distance of the crystals is also approximately constant.

This has the advantage that the pressure change in the plateau region is extremely small compared to conventional alloys, and the amount of hydrogen that can be used for practical purposes is large.Moreover, the reaction rate with hydrogen during the hydrogen absorption and release process is fast, making it highly reactive. It has the characteristics of shortening the completion time.

That is, the present invention has developed a Mitshu metal (hereinafter abbreviated as Mm)-nickel quaternary alloy by treating it under various conditions and examining the effect on pressure changes in the plateau region. The present invention has been completed based on the discovery that the above-mentioned conventional drawbacks can be overcome by heat treatment for a short time at a temperature below the melting temperature of .

The present invention is a method for producing a Mitshu metal-nickel based quaternary alloy for hydrogen storage, which comprises heating an alloy represented by the general formula MmN i 5-, 8-yBy to a temperature of 500 to 1000°C and then cooling it. be.

However, the ceremony name is Mitsushmetal, A is kl, Co
, Cr, Mn and Si, B is an element selected from the group consisting of Ae, Co, Cr, Cu, Fe
, represents an element selected from the group consisting of Mn and Si,
A and B are always different elements, and A is A6 t Cr
+ When Mn and Si, X is a number in the range of 0.1 to 2;
y is a number in the range of 0.01 to 1,99, and when A is Co, X is a number in the range of 0.1 to 4.9, y is 0,01 to 4
．． It is a number in the range of 89, and X is thicker than y.

The raw material alloy used in the present invention is Mm, nickel, Ae
, Co, Cr, Mn and Si and elements A1 and Ae, Co, Cr
, Cu, Fe.

It is a Mitsushi metal-nickel based quaternary alloy consisting of an element B selected from the group consisting of Mn and Si, which is always different from the above A, and the general formula % is 0.1 to 2 + Y is 0.01 to 1.99. is a number in the range of .

When X is less than 0.1, the properties are only close to those of MmNi5, and the effect of adding metals A and B cannot be obtained.

In other words, since MrnNi5 hydride has a high dissociation pressure, activation requires applying high pressure hydrogen after sufficient degassing, holding it at low temperature in a hydrogen atmosphere, or a combination of both. creating disadvantages.

When X is 2 or more, although the ease of activation is maintained, the hydrogen storage capacity is reduced and it becomes difficult to release the stored hydrogen, resulting in the problem that high temperature heating and sometimes depressurization must be combined with this.

Also, when y is less than 0.01, MmNi5-xAx (A is A
4, Cr, Mn, and Si), and the effect of adding metal B cannot be achieved.

In other words, the rate of hydrogen release becomes slower.

When y is 1.99 or more, the hydrogen storage capacity is significantly reduced, making it difficult to release the stored hydrogen, resulting in the problem of requiring high-temperature heating and sometimes a combination of pressure reduction.

Furthermore, when A is Co, X is 0.1 to 4.9. y is 0.01
~489 numbers.

Of course, in all cases X > y.

If X is less than 0.1, the properties only close to those of MmNi5 are exhibited, and the effect of Co addition cannot be achieved.

That is, activation requires the application of high-pressure hydrogen, maintenance at low temperatures in a hydrogen atmosphere, or a combination of both, which is a disadvantage.

When X is 49 or more, it exhibits characteristics close to those of Mm Co 5, resulting in the problem that the amount of hydrogen storage is approximately half that of MmNi 5.

Also, when y is less than 0.01, N1rnN t , -x C
It exhibits only characteristics close to those of ox, and the effect of adding metal B cannot be achieved.

In other words, the rate of hydrogen release becomes slower.

When y is 4.89 or more, the hydrogen storage capacity is significantly reduced, and it becomes difficult to release the stored hydrogen, resulting in the problem that high-temperature heating and sometimes depressurization must be combined.

The present invention is carried out by heating the Mitshu metal-nickel based quaternary alloy to 500 to 1000°C and cooling it.

Heating may be carried out in the presence of air, but if the surface layer of the alloy is oxidized, heating should be carried out in an inert range such as under reduced pressure, in the presence of an inert gas, or a combination of both. It is preferable.

Heating may be performed by any method, for example, using a siliconite or nichrome heating element electric furnace.

The heating temperature depends on the combination with the heating time, but it is usually 5.
00 to 1000°C, preferably 700 to 1
000°C, more preferably 800-1000°C, most preferably 900-1000°C.

If the heat treatment is carried out for a long time at 500° C. or lower, the same effect as the treatment in the above temperature range can be obtained, but this is not practical for mass production of alloys.

Furthermore, at temperatures above 1000°C, if the alloy contains components such as ke, Cr, and Mn, which have relatively high vapor pressures,
Part of it volatilizes, increasing the dissociation pressure of the hydride, and making it impossible to obtain an alloy with the desired composition.

The heating time is determined from the relationship with the heating temperature, and the heating time is 1000°C within the range of 500 to 1000°C.
If the temperature is close to 500°C, it may take a short time; if the temperature is close to 500°C, it may take a long time, but generally it is in the range of 0.25 to 6 hours.

If it is less than 0.25 hours, the effect of the alloy heat treatment tends to decrease, and if it is more than 6 hours, there is no difference in the heat treatment effect.

For cooling after heating the alloy, it may be rapidly cooled in ice water immediately after heating, or it may be slowly cooled in air.

The components of the alloy used in the present invention (■) are general nilanthanum 25 to 35% (by weight, the same applies hereinafter) and cerium 40 to 35%.
70%, praseodymium 1-15, neodymium 4-1
5%, samarium + gadolinium 1-7, iron 0.1-
It contains 0.1% to 1% silicon, 0.1% to 2% magnesium, 0.1% to 1% aluminum, and can be easily and inexpensively made by hand.

Moreover, the alloy MmN i , -8 used as a raw material in the present invention
Ax-7B can be manufactured by various known methods, such as an argon arc furnace method.

That is, blood, nickel, and the metals A and B are mixed in powder form or in an appropriate form, such as a rod, so as to have the alloy composition described above, and then press-formed into an arbitrary shape, and this molded product is heated in an argon arc. The material is charged into a furnace and heated, melted, and allowed to cool several times in an inert atmosphere to homogenize the composition, and then taken out from the furnace and used as a raw material alloy.

According to the method of the present invention, excellent effects can be imparted to the MmNl5-XAx-yBy-based alloy through relatively simple operations.

In other words, by heat-treating the raw material alloy at 500 to 1000°C and cooling it, the unstable lattice gaps that occur during alloy production disappear and a single-phase alloy is obtained, and the interstitial distance between the crystals also decreases. Since it remains almost constant, it has the advantage that compared to conventional alloys, there is extremely little pressure change in the flat or plateau region of the hydrogen storage and dissociation pressure characteristics at a constant temperature, and the amount of hydrogen that can be used for practical purposes is large. are doing.

Moreover, since the reaction rate with hydrogen during the hydrogen absorption and desorption process is fast, the reaction completion time is shortened, and the hydrogen absorption reaction is completed in a short time.

Furthermore, no matter how many times the hydrogen storage and release reactions are repeated, there is virtually no deterioration of the alloy itself, so it can be used for a long period of time, making it extremely excellent as a hydrogen storage alloy.

Furthermore, the method of the present invention can be applied not only to the -nickel-based quaternary alloy, but also to ternary or higher hydrogen storage multi-component alloys containing -X and Ni as main components, such as Mm, -XAXNi5. Mm
l-xAxNi5-yBy 1Mm +, -x A
x -z Cz N i5 tMm l -xA X
-Z Cz N 15- y B y 1Mm1-xA
xNi 5-, E3. -2c2 (A, B and C are different elements) and the like can be used in the same way.

Next, examples of the present invention will be described.

Example 1 Conventional alloy M manufactured by argon arc melting furnace method
mNi4.5 Mn0.25 Cr0.25.

MmNl4.5 Ag, 25Mn□, 25. MmNi,
5Ae□, 25SiO, 25゜MmNl4.5A6o,
25 FeO, 25, MmNl4, 5 Mo, 25Cu
O,25 and MmN I 2.5 Co2. oAe
□ and 5 were placed in a quartz container, and after introducing argon into the container to sufficiently replace the gas inside the container, the inside of the container was maintained at a pressure of 1 torr using a vacuum device.

This container was placed in an electric furnace previously maintained at 900° C. and heat treated.

After 2 hours, the heat treatment was stopped and immediately cooled in ice water to obtain a heat treated alloy.

Table 1 shows the influence on the heat treatment effect when the heat treatment temperature and treatment time are changed in this way.

Note: Heat treatment effect is 900℃, 2 hours heat The effect that appeared under the treatment conditions is set as 100. I compared it.

A: 90-100% 8170-90% C: 50-70% D: 50% or less As is clear from Table 1, the heat treatment temperature is 500-100%.
All of the heat-treated alloys obtained under the conditions of 0°C and a treatment time of 0.25 hours (15 minutes), preferably 6 hours, had a significant treatment effect, as shown in Figures 1 to 3 below. It has good crystallinity, very little pressure change in the plateau region of hydrogen storage pressure-composition isotherm, and fast hydrogen storage rate.
It is an excellent hydrogen storage material.

Example 2 a) 1 t of conventional alloy MmN i4,5Ae, 25F'eo, 25 manufactured by v-bond arc furnace melting method
Heat treatment was performed at 900° C. for 2 hours in an argon atmosphere.

FIG. 1 shows the powder X-ray diffraction diagrams of this heat-treated alloy and a conventional alloy that was not heat-treated.

As is clear from Figure 1, the X-ray diffraction pattern of the alloy heat-treated according to the present invention has a sharper shape than the X-ray diffraction pattern A of the alloy that has not been heat-treated, and the half-width of the peak is significantly larger. It can be seen that the crystalline phase becomes much smaller and has a homogeneous crystalline phase.

Example 3 MrnN14.5 k136. subjected to the heat treatment of Example 2.
25 peo, 25 was heated and degassed at 80°C under reduced pressure, and after being sufficiently activated with hydrogen, MmNi4.5A11? o, 2. The storage pressure car hydride composition isotherm (40°C) of the Feo, 25H system was compared with that of the alloy without heat treatment.

The results are shown in Figure 2.

Conventionally, it is known that when part of the nickel in Ni5 is replaced with another element, the pressure gradient in the plateau region becomes steeper as the substitution progresses; for example, in the MmNi5-xAx yBy system. For alloys, the slope of the plateau region increases progressively as X increases in the range 0.1-2.

However, as shown in FIG. 2, the pressure change in the plateau region of the hydrogen storage pressure-composition isotherm A of the heat-treated alloys of the present invention; MmNi4.5Aeo, 5Feo, and 25 is 30
50 atm, while the isotherm B of the conventional alloy without any other treatment varies greatly in the range of 1.3 to 9.0 atm, indicating that the alloy according to the present invention is a hydrogen storage material. It is clear that it has extremely excellent properties.

Example 4 The reaction rate of the alloy MmNi4,5Ae, 25FeO,25, which was heat-treated in Example 2, during hydrogen storage was measured.

MrNi4.5Aeo, 25F without heat treatment
A comparison with that of eo, 25 is shown in FIG.

As is clear from FIG. 3, the hydrogen storage reaction rate A of the heat-treated alloy completes the reaction in approximately 1/2 the time of the reaction rate B of the non-heat-treated alloy.

[Brief explanation of the drawing]

FIG. 1 shows alloys obtained by the method of the present invention and the conventional method, M111N14.5Aeo, 25Feo, 2. 2 is a hydrogen storage pressure-hydride composition isotherm diagram of these alloys, and FIG. 3 is a diagram showing the relationship between hydrogen storage rate and time of these alloys.

Claims (1)

[Claims] 1 General formula Mrn' N t 5- x Ax -y
A method for producing a Mitshu metal-nickel based quaternary alloy for hydrogen storage, which comprises heating an alloy represented by B y to a temperature of 500 to 1000°C, and then cooling the alloy. However, ■ in the formula is Mitsushmetal, A is A6゜Co,
An element selected from the group consisting of Cr, Mn and Si, B is Ae3. Co, Cr, Cu, F
e indicates an element selected from the group consisting of Mn and Si, A and B are always different elements, and A is Ae,
Cr. When Mn and Si, X is a number ranging from 0.1 to 2, y is a number ranging from 0.01 to 1.99, and when A is Co, X is a number ranging from 0.1 to 4.9. number, y is 0.01 to 4.8
A number in the range 9, where X is greater than y.